Project 1: Studies were directed toward characterization of functionally important domains of the transforming protein p21, coded for by the members of the ras/bas gene family. Antibodies were raised against a synthetic peptide generated from the amino terminal, middle and carboxy terminal segments of the p21 molecule encoded by v-bas/v-ras transforming genes. The GDP binding function and GTP/ATP-mediated autophosphorylation of p21 was completely blocked in the immunoprocipitates brought down by c-terminal peptide antibodies, in contrast to the retention of these functions in immunorecipitates brought down by a monoclonal antibody (YA-6-172) to Harvey murine sarcoma virus (Ha-MSV) p21. These observations suggest that the GTP-binding/autophosphorylation of the Ha-MSV p21 is modulated by the c-terminal domain of the protein molecule. Project 2: The transforming gene of human lung carcinoma-derived cell line Hs242 has been cloned in biologically active form and identified as c-bas/has. The genetic lesions responsible for the transforming activity of the Hs242 oncogene have been localized to a point mutation in the second exon, which results in the substitution of leucine for glutamine.